Internal grinding machine



April 1950 T. H. LJUNGGREN 2,502,862

INTERNAL GRINDING cam:

Filed Oct. 5, 1946 7 Shuts-Sheet 1 Ap 4, 1950 1'. H. LJUNG'GREN 2,502,862

INTERNAL GRINDING MACHINE Filed Oct. 5, 1946 I 7 Sheets-Sheet 2 April 4, 1950 "r. H. LJUNGGREN INTERNAL GRINDING MACHINE 7 Sheets-Sheet 3 Filed Oct. 5, 1946 I L ihwmmwv4 April 4, 1950 'r. 'H. LJUNGGREN INTERNAL GRINDING MACHINE '7 Sheets-Sheet 4 Filed Oct. 5, 1946 April 4, 1950 T. LJUNGGREN INTERNAL GRINDING MACHINE 7 Sheets-Sheet 5 Filed Oct. 5, 1946 April 4, 1950 1'. H. LJUNGGREN INTERNAL GRINDING MACHINE 7 Sheets-Sheet 6 Filed Qct. 5, 1946 r kg 3 b &

. Q $1 R %Q a 5 R @N \w% RN @OMN 7 Sheets-Sheet 7 April 4, 1950 1- H LJUNGGREN INTERNAL GRINDING MACHINE Filed Oct. 5. 1946 Patented 4, 1950 UNITED STATES PATENT OFFICE INTERNAL GRINDING MACHINE Thor H. Ljunggren, Springfield, Vt, asslgnor to Bryant Chucklng Grinder Company, Springfield, Vt;, a corporation of Vermont Application October 5, 1946, Serial No. 701,443

6 Claims. 1

This invention relates to internal grinding machines and has for an object to provide a machine of this type wherein a portion, at least, of the machine cycle may be controlled by the action of sizing plug gages which are periodically brought into engagement with the work and when the work is brought to a size at which one or more can enter the work, changes in the machine cycle are or may be initiated.

Another object of the invention is to provide for selective use of plus and diamond sizing.

A further object is to provide improved combined hydraulic and electrical control mechanism for the machine.

Further objects and advantages will appear from a description of an embodiment of the invention shown in the accompanying drawings in which Figure l is a front elevation of a machine embodying the invention.

Figure 2 is a top plan view of the same.

Figure 3 is a left hand end elevation of the upper portion of the machine.

Figure 4 is a detail sectional view to a larger scale of the left hand portion of the machine on line 4-4 of Figure'2.

Figure 5 is a detail sectional view on line 55 of Figure 4. I

Figures 6, 7, and 8 are diagrammatic views illustrating relative positions of certain parts when the plug gage is moved to gage the work and when the hole in the work is respectively under rough grinding size, at rough grinding size, and at finish grinding size.

Figure 9 is a view partly in front elevation and partly broken away of the work gage feed mechanism, this view being to a larger scale than Figure 1 Figure 10 is a detail sectional view on line Ill-l 0 of Figure 9.

Figure 11 is a detail H-ll of Figure 10.

Figure 12 is a detail sectional view on line |2-|2 of Figure 9.

Figure 13 is a fragmentary left side elevation of a portion of the feed mechanism shown in Figure 9.

Figure 14 is a detail sectional view on line "-44 of Figure 13.

, Figure 15 is a diagrammatic view showing the sectional view on line 2 electric and fluid pressure controls and actuating mechanism at the beginning of the grinding cycle.

Figure 16 is a diagram of the phases of the cycle control mechanism.

Referring to the drawings, at I- is indicated a machine base on which is mounted e traversing carriage 2 which supports a wheel head 3 carrying a grinding wheel spindle 4, upon the outer end of which is mounted a grinding wheel 5. As shown the head 3 is mounted on the carriage 2 for adjustment backwardly and forwardly, being supported on ways on a face portion 6, in which ways it is held by a locking strip 1 (see Figure 4) held against a foot 8 of the wheel head as by screws 9.

The traversing carriage 2 carries a bar ID, the opposite ends of which are formed hollow as at H thereby providing hydraulic cylinders within which extend plungers l2 having passages l3 therethrough with which communicate fluid pressure pipes I 4. The plungers [3 are secured in caps l5, which, in turn, are secured to the bed I as by screws IS.

The bed I is also provided with transverse ways I! on which is mounted a transversely movable carriage I8 provided with longitudinal ways I9 for the reception of a work head 20. The carriage I8 is supported on rollers and is guided along a guide strip 26 against opposite edges of which bear guide rolls 2! and 28. The specific mounting of this carriage [8 forms no part of the present invention and is therefore not further described herein, but forms subject matter of my application for United States Letters Patent Serial No. 680,502 for Carriage mounting, filed June 29, 1946.

The work head 20 has Journaled therein a work spindle 30 provided with a standard spindle nose at 3| to which a chuck 32 of any suitable description may be attached as by the screws 33. As shown this chuck is adapted to support a work piece 35 having a central bore adapted to be ground by the grinding wheel 5. The spindle 30 is hollow and carries within a pair of sleeves 38 and 31 therein, which are threaded together, a feeier rod 38 adapted tosupport at its outer end a stepped plug gage 39. This plug gage may have an outer smaller diameter portion 40 (see Figures 6, 7 and 8) of a size to just enter the work when it has been rough ground and an inner larger diameter portion H of a size to just enter the work when the work has been ground to finish size. As will later appear, this plug gage may be brought up to the work piece periodically during the grinding operation so that as soon as the work reaches the size for rough grinding, the smaller diameter 48 will enter the work and as soon as the work reaches final finish size, the larger diameter portion M will enter the work. When either of these actions occurs, changes are made automatically either to withdraw the grinding wheel for truing when the work reaches the rough grinding size, or to withdraw the wheel for replacement of the work when the work reaches finished size.

Axial motion of the plug gage is in time with the reciprocation of the grinding wheel during its traverse, and for this purpose, the left hand end of the member I8 shown in Figure 4 impinges upon a rod 58, which is slidably guided through a cylinder 5I. As shown this rod passes through a hollow piston rod 52 having a piston 53 thereon, slidable within the cylinder 5|, the piston rod 52 passing through opposite ends of the cylinder II. This rod 58 carries a collar 54 having a peripheral groove within which rides a ring 55 mounted on trunnions 58 riding in a peripheral slot in a bell crank lever 51. This bell crank lever is journaled at 58 on the fixed bracket 59 and carries at its outer end a cylindrical bar 88 on which rests the head 6| of a rod 82 mounted for vertical sliding through a supporting bracket 63 secured to the outer end portion of the work head 28. Within the work head the rod 82 is connected through a link 64 to a bell crank lever 65 fulorumed at 65 and having a bifurcated arm 81 (see Figure 5), the forks carrying a pair of rolls 58 which ride in a slot 89 in a block 18. This block 18 is adjustably secured to the rear end of the rod 38 which carries the plug gage. This rod 38 is normally pressed axially toward the work, as by a coil spring 1I (Figure 5) having one end, as at 12, engaged with a portion of the bell crank lever 85, its other end being anchored in a collar 13 pinned to the fulcrum shaft 85 on which the arm 65 is journaled, this shaft 66 being held against rocking motion by a pin 15 which secures it to a supporting bracket portion 16 integral with a portion of the work head.

As the grinding wheel moves axially toward the gage, the corresponding motion of the bar I8, acting on the rod 58, rocks the bell crank lever 51 in a direction to lift the rod 82, which rocks the bell crank lever 85 in a direction to retract the rod 38 which carries the gage, but as the grinding wheel retracts from the gage, or moves to the right as viewed in Figure 4, the rod 38 is allowed to move in the same direction either to contact with the work while the holes in the work are too small to allow the plug gage to enter, or to allow the plug gage to move further to the right in case the plug gage can enter the hole in the work. This rod 38 is so mounted that it can rotate with the spindle, being rotatably mounted within the block 18. By this means the wear on the gage is reduced to a minimum since it rotates with the work. The work spindle is shown as having keyed thereto a drive pulley 88 by which it may be rotated, and this may be done by belt drive from a motor 8| (shown in Figure 2), the belt drive being housed within the casing 82.

The block 18 is provided with an upstanding flange 85 (see Figures 4 to 8), and this flange carries a pair of adjustable stop screws 88 and 81. The stop screw 88 is the screw corresponding 4 to rough grinding work size, while the stop 81 corresponds to the flnished worksize. They are so positioned as to impinge upon sliding contact members 88 and 88, respectively. The stop screw 88 extends further through the flange than the stop 81 so that it impinges upon its contact 88- whenever the flange 85 moves to the right 0 distance corresponding to that motion of the rod 38 at which the smaller diameter portion 48 of the plug gage enters the work, this being in theposition shown in Figure 7. At this time the screw 81 is so retracted that it does not contact and move the contact slide 89. This extent of motion of the flange 85, corresponding to rough grinding size of the work as shown in Figure 7, closes contact between a pair of terminals 98 and 9|, which closes certain circuits effective, as will later more fully appear, to cause the grinding wheel to be retracted axially from the work, during which motion it is trued and is thereafter again brought into operative position for the finish grinding operation. When the work piece is ground to finished size so that the larger diameter portion H of the plug gage is able to enter the work, as shown in Figure 8, the flange 85 moves a corresponding distance, pushing the slide 88 beyond its closed contact position of Figure '7, where the contacts 98 and 9| are again electrically disconnected, but the stop screw 81 is in this position efiective to move the slide 89 into position to electrically connect the terminals 92 and 93, which, as will later appear, is effective to cause withdrawal of the grinding wheel and the stopping of the machine.

However, as will later more fully appear, the plug gage may be held out of operative position when desired, this being accomplished by introducing fluid under pressure into the cylinder 5I through the port 98, causing the rod 58 to be retracted out of contact with the bar I8, lifting the rod 62 and holding the rod 38 with its plug gage in retracted position, regardless of the position of the bar I8 and throughout the traverse motions of the wheel 5.

When desired, the plug gage may be rendered inoperative entirely, or for rough grinding only, and feed limit stops substituted. Where the feed limit stop is employed for final sizing, it acts to determine the size by a predetermined extent of wheel feed after truing of the wheel has been effected, this being known in the art as diamond sizing." The means for doing this will later be described.

The feed motion between the grinding wheel and the work is produced by transverse motion of the work head, and this feed mechanism is shown particularly in Figures 1 and 9 to 13.

The machine base I, supporting the carriage I8, shown best in Figure 12, is provided with an upstanding portion I88 within which is journaled in a bushing I8I, a nut I82 threaded upon a lead screw I83. This nut I82 has an end flange I84 seated in a recess I85 in the inner face of a gear I88 to which it is secured as by screws I81. This gear meshes with a gear I88 carried by a shaft I89. Integral with the gear I88 is a pinion II8 with which meshes the teeth of a rack bar III. This rack bar III, as shown best in Figures 1 and 15, is part of a piston rod having a piston I I2 which rides in a horizontal hydraulic cylinder II3, the piston rod III extending through both ends of the cylinder. At one end this rod may contact at a desired limit of feed with one or the other of a pair of stops 335, 388 carried by a member I348 movable between a position to pre- 300. which projects grinding stop 335, into line th the rod as: to present the'finish grinding stop as into line.

Mechanismfor controlling the position of the" member I340 and for moving it from one to the There is also provided means for producing an additional small feed motion to compensate for the reduction in size of the grinding wheel due to wear and truing. This additional small feed is accomplished by effecting rotation of the lead screw I03, the main feed, as before noted, being produced by rotation of the nut relative to the screw. The outer end portion of the lead screw I03,\as shown in Figure 12, is keyed to a hub I I5 of a hand wheel I I0, and by which the lead screw may be turned by hand as in setting up the machine. Thi hub III has secured thereto a worm wheel Ill, and a worm IIO carried by a worm shaft I (see Figure 9) is normally in engagement with the worm wheel IIO. This shaft I20, however, is connected through a flexible coupling comprising a metallic bellows I2I keyed at I22 to the shaft I20 at one end and secured at its other end to a collar I23 pinned to a shaft I24 journaled in a portion of the machine frame. This shaft I 24 has a ratchet wheel I25 keyed thereto and cooperating with this ratchet wheel i a ratchet dog I20 (see Figure 13) mounted on a lever I21 fulcrumed at I20 to an extension I29 from a disk I30 iournaled on a bushing I3I carried by the shaft I24. This disk I30 is secured as by a screw I32 to a collar I33 journaled on the bushing I3I and being provided with a pinion portion I34. In mesh with this pinion portion is a vertical rack bar I35 which forms a portion of a piston rod I30 extending into a hydraulic cylinder I31 and provided with a piston I30 on its lower end which rides within the cylinder I31. This piston and piston rod are normally held elevated as by a spring I seated in its upper end in a socket I in the piston rod I30 and on its lower end on an abutment collar I42 carried by an abutment rod I43 threaded through the lower end cap I44 of the cylinder I31. This mechanism may be rendered inoperative when desired by lifting and locking the ratchet dog I20 in inoperative position by engaging the slidable pin I40 (Figures 13 and 14) in the socket I41 in the extension I 29.

when fluid under pressure is admitted to the cylinder I31 above the piston I30, as through the pipe I40 and passage I41, the piston with the rackbar I35 is driven downwardly, rocking the gear I 34 and correspondingly turning the ratchet wheel I25 with the shaft I24 and the worm H3, provided this wheel is allowed to mesh with the worm wheel.

When it is desired to rotate the feed shaft I03 by hand, this worm II! is lifted out of engagement with the worm wheel, as otherwise this worm wheel would be locked against rotation by the worm. This may be done by lifting the outer end portion of the supporting bearing I through which the shaft I20 is journaled and which is vertically slidable in a slot IOI in the machine frame, this action being permitted by the flexing of the bellows I2 I. As soon as the frame portion I50 is allowed to drop back to position to engage the worm wheel II 0, the feed shaft I03 is locked against further rotation except by rotation of the worm H9. As will later appear, this worm is atoasoa,

' the sleeve against the gear the crciejin-order to II5 by a clamp'serew "(threaded through the I I0and africti'on shoe I55 enga ng the outer end face of the sleeve! 52 and forcing It may be desired to control the feed speed to produce a rapid feed while the wheel is out of contact with the work and then a slow feed to contact and grind the work and the termination of the fast feed may be independently controlled for the rough and finish grinding. Means for so doing is shown in Figures 9 to 11 and diagrammatically on Figure 15. For this purpose the end of the shaft I03, as shown in Figure 10. extends through and is pinned to a disk I00. Back of this disk I00 a pair of arms IOI and I02 are rockably mounted on the shaft I03. This disk I00 has a pair of arcuate slots I03 and I04 therethrough through which extend thumb screws I05 and I00. The thumb screw I05 extends through a spacing collar I01 between it and the arm IOI and is threaded into the arm IOI. By loosening the thumb screw I05, the arm I'0I may be freed from the disk I00 and adjusted to any arcuate position relative to the disk I00 within the limits of the slot I03. correspondingly the thumb screw I00 which passes through the slot I04 is threaded into the arm I02, so that on loosening this thumb screw I00, the arm I02 may be adjusted angularly within the limits of the slot I04. The arm IOI has fixed thereto an end flange I10 of an arcuate dog Ill, and the arm. I02 has fixed thereto a similar end flange I 12 of an arcuate dog I13. These dogs "I and I13 partially surround a hub portion I14 and they have tapered edge portions I 15 and I10 which are adapted to com tact cam follower rolls I11 and I10 of electric switch actuating elements I19 and I00.

As will later appear, the dog "I may be arranged to actuate a switch which controls the slowing of the feed for a rough grinding operation. The arm I 02 is then set ahead through a desired arc, as shown on suitable graduations on the disk I00, so that after wheel truing action, fast feed proceeds through a predetermined angular turning of the shaft I03 and consequent angular turning of the feed nut I02 until such time as the dog I 13 acts on a fast feed switch, reducing the fast feed motion to a slow feed for the finish grinding operation. This mechanism per se is not my sole invention and is therefore not claimed herein.

A wheel truing device 0 is shown in Figures 2 and 3. This device is carried by an arm 4 horizontally fulcrumed at 2 to swing down into the horizontal operative position shown where the wheel 5 will pass across it during the extended truing stroke, or to be rocked upwardly into idle position. For so moving the truing device, the arm 4 has engaged therewith the piston rod 219 of the fluid pressure motor 210, fluid pressure introduced into the right hand end of this motor pulling the rod 213 and lowering the truing device, a spring 4 acting in the opposite direction, moving thetruing device to inoperative position when pressure is released to the motor 210.

7 Cycles of operation The length of strokeof the wheel slideis determined by certain stop dogs of different lengths shown diagrammatically in Figure 15 and carried The longest of these dogs limit of stroke during the normal grinding operation. Next is the stop of intermediate length 202, which determines the length of limit of outward stroke during the wheel dressing operation. All these stops cooperate at suitable times with an eccentrically disposed follower 203 carried by a rockable and vertically movable member 2. This member 204 carries a long gear 205 which in all axial positions meshes with a rack bar 208 carried by a reversing valve 201 which determines the direction of traverse at any particular time. This member 204 extends into a vertical cylinder 2 I within which is slidably mounted and carried by the member 204, a valve 2| I. The lower portion of this valve is hollow and may rest upon a piston 2I2 slidable within the cylinder 2I0. A fluid passage and pipe 2 I4 leads into the cylinder 2I0 between the piston 2I2 and the under face of the valve 2I I. The piston 2I2 has an air escape passage 2 I 5 therethrough leading into the hollow in the lower end of the valve 2 I I. The valve 2| I is capable of taking any one of three positions of elevation, moving the member 204 therewith. It is shown in Figure as in the intermediate of these three positions, with the piston 2I2 lifted to its limit from the lower end of the cylinder 2I0, but with the valve 2 engaging the piston 2 I2. By admitting fluid pressure above the piston 212 while the piston is down, the valve H I may be raised to its highest position, or by discharging fluid from both sides of the piston 2I2, the piston 2I2 may descend to the bottom of the cylinder 2I0 while the valve 2 still rests upon it, this being the lowest position.

In the highest position, the stop I will engage the follower 203 at the outer limit of wheel slide motion, preventing the wheel slide from moving to its extended limit of retracted traverse shown in Figure 15, in which both the dogs 200 and 2 are effective to contact the follower 203 and rock it back and forth to reverse the directions of traverse of the wheel slide.

In the intermediate vertical position shown, while the dog 200 is effective at the inward limit of motion, the dog 202 instead of the dog 20I is effective at the outer limit and the wheel slide is given an extended stroke separating it from the Work, and during this extended stroke the wheel is trued.

In the lowest position of the member 204, the dog 200 is th only dog effective, this limiting the inward stroke of the wheel slide, the outward stroke passing the dog 202 and to a point where the wheel slide comes to rest at the end of the grinding operation for the removal and placement of work. There is nothing at this end of the stroke to reverse the direction of traverse automatically, the reversal being done by the operator at the start of the next cycle of operations. This arrangement is not claimed herein as it forms subject matter of my application Serial No. 455,737, for Grinding machines, filed August 22, 1942 and which issued as Patent No. 2,429,830 on October 28, 1947.

The fluid pressure for producing this reciprocation of the wheel slide is derived from any suitable source, but as shown in Figure 15 is taken froma supply tank 220 by a pressure pump 22I into a pressure pipe 222.

The pressure pipe 222 leads to various hydraulically operated devices, one of which comprises the reversing valve 201 to which it communicates at two axially spaced positions 223 and 224. In the position of the mechanism shown in Figure 15, the pipe 223 is blocked off by the valve, but the pipe 224 is opened to the pipe 225 which leads to the right hand end of the bar In in the right hand cylinder I3a, thus to drive this cylinder and the wheel head toward the left. At the same time fluid under pressure escapes from the left hand cylinder I3a through the pipe 226 past the valve 201, the pipe 208, past the valve 2I I to the pipe 209, through the dressing throttle valve 221 which slows down the traverse motion to. the desired point, out through the pipe 222 to the discharge pipe 229, leading back to the tank 220. The pipe 209 also has a branch 230 leading to the lower portion of a valve 23I, but this is blocked off by the valve plunger 232 at this time, so it is ineffective.

The pressure pipe 222 also leads to a series of ten hydraulic valves A, B, C, D, E, F, G, H, J

and K. In the particular positions of the parts shown in this figure corresponding to extended traverse for wheel dressing, the valves A, B, C, G and J are in raised position and are so held by the energization of corresponding solenoids. The various solenoids for lifting the valves A to K, inclusive, are electrically actuated from a power line 235 through a series of rotary switch actuators 236af, each secured to a shaft 231 which at one end carries a ratchet wheel 238. A solenoid 239 when energized is effective to turn the ratchet wheel 23!; step by step, each upward movement of the ratchet dog 240 serving to turn the ratchet wheel 238 one-eighth of a revolution. The shaft 231, together with the rotary switch actuators 236aj constitutes a cycle control mechanism which is effective to actuate the solenoids for lifting the valves A to K in predetermined sequence, this sequence determining the cycle of operations of the machine. It will be noted that reading from the left of Figure 15, the first of the disks 236 has four switch actuating projections thereon, the next three have two projections each, the next has four such projections, and the disk nearest to the ratchet wheel 230 has eight such projections.

It will be noted from an inspection of Figure 16 that there are two complete cycles for each complete rotation of the cycle control mechanism as follows: load, rough, dress and finish. Each of these in Figure 16 has the designation a, b, c, d, and the switch actuating projections on the corresponding disks 236a, 236b, 2360, 236d, 236e, 235i, which are active in closing their switches, are similarly labeled on Figure 15. Turning of the cycle control mechanism is initiated by energization of the solenoid 239, but as the impulse that energizes this solenoid from the various mechanisms may be of short duration, the rotary switch actuator 236 has been employed, this having the effect of imparting a second energizing impulse to the solenoid 239 at each actuation, which is sufficient to complete a full turning stroke of an eighth of a revolution of the ratchet wheel 238. Each of the projections on this switch actuator 236! closes a switch 245 which connects from the power line 235 through 7 the lead 246 connecting to the solenoid 239. By

ators 236a. and 236c are in the time the turning action is complete, however,

the switch 245 is opened again so that the ratchet 240 is allowed to return to its initial position ready for the next turning actuation. The rotary switch actuators 236a, 236b, 2360, 236d and 236a eflect the controls of the apparatus to determine the operative cycles.

The conditionof the parts shown in Figure is for the Dressing step of the cycle. In this step the switch closing projections c of the actuswitch-closing position, this closing the switches 250 and 252. The closing of the switch 2511 establishes a circuit from the power line 235 through the switch 250, lead 260, the solenoid 261 of the valve A, lifting this valve so that fluid pressure from the pressure pipe 222 passes this valve A, through the pipe 96 to the plug retractor cylinder 53, thus holding the plug retracted during the truing operation. Connection is the lead 260 to one side 262 which is opened at phase in which position the grinding wheel is at its inner limit of stroke within the work.

The closing of the switch 252 by the disk 2360 conducts power from the power line 235 through switch 252, and the lead 265 to one side of a switch 266, which may be closed by contact from a cam 261 carried by the wheel slide when the wheel slide has been retracted to a predetermined extent. When so retracted and closing the switch 266 as shown, connection is made through leads 268 and 269 to a solenoid 210, raising the valve 232 so that the discharge from the traverse motor through the pipe 230 is closed oil. through the grinding throttle valve 21 I and must pass through the dressing throttle valve 221, back to the discharge line 228. This lead 268 also connects to the solenoid 215, raising the hydraulic valve B, this allowing pressure to pass from the pressure pipe 222 past the valve 216 into the pipe 211 leading into diamond holder mechanism 218 in position to pull the truing device attached to the piston 219 into operative relation to true the wheel as it is retracted during an extended traverse. This extended traverse is produced by energization of the solenoid 281 of the valve J connected to the lead 265 through the lead 280 leading to the solenoid 281. This raises the valve J, which connects the pressure line 222 past the valve 282 through the pipe 285 into the cylinder 210 beneath the piston 212, while the pipe 214 connecting in between this piston 212 and the valve 211 is open to discharge past the valve 286 through the pipe 281 around the valve 282 and through the pipe 288 to the discharge pipe 228. The member 204 is thus in its intermediate position where its element 203 is stopped at the outer limit of stroke by the dog 202 against which it strikes to reverse the direction of traverse as previously explained, the stop 200 determining its inner limit of stroke as it does in all axial positions of the control member 204. It is during this extended portion of its stroke between the dogs 201 and 202 that the cam 261 is effective to close the switch 266 which has the effect of placing the diamond holder in operative position and to reduce the speed of traverse to that set by the throttle valve 221.

At this time, also, the wheel is retracted from the work, the feed piston 112 in the cylinder H3 being in the position shown, the rear end of the cylinder 112 being connected by the pipe 290 past the valve F through the pipe 292 to the discharge pipe 228, while the opposite side of the feed cylinalso established through of the cycle start switch the start of the truing' der is connected through the pipe, 288; past the valve E and the pipe 265 to the pressure pipe 222. When the wheel feed is in fully retracted position the rack 111 closes a switch at 286 which completes a connection throughlead 261 from the lead 280, to a lead 296 through solenoid 288 of the valve C, lifting this valve and allowing fluid pressure from the pressure pipe 222 to pass this valve and reach the compensator cylinder 131 through the pipe 146, thus to produce a feed component to take care of wheel wear and tming.

As the wheel slide retracts, a pivoted dog 300 carried thereby contacting the switch 262. is retracted so that this switch 262is not'actuated, but on the return stroke, after. the element 202 has been contacted by the stop 202 andhas been moved thereby to reverse the traversedirection, an inclined face 301 of'the dog 300 engagesthe switch 262 and as the dog cannot retract in this direction of motion, the switch 262 is depressed, closing electrical connection between the lead 260 and the lead 305. This lead 305 connects to the lead 246 and thus passes current to the solenoid 239, energizing this solenoid and stepping the cycle control mechanism around an eighth of a rotation, placing the cycle control mechanism in Finish grind position. This causes the switches 250 and 252 to open, but closes the switches 253 and 254, the corresponding rotary switch actuating disks 236d and 236e having switch-actuating projections d thereon. The closing of the switch 254 establishes a connection from the power line 235 through the switch 254 to a lead 310 which passes to a solenoid 311, energizing this solenoid and lifting the valve K. This causes pressure from the pressure pipe 222 to pass through the pipe 315 around the valve J, which is now depressed because its solenoid 281 was deenergized on the opening of the switch 252, through the pipe 316, past the lifted valve K into the pipe 214 and into the cylinder 210, lifting the member 204 to its top position where the outer limit of traverse of the wheel slide is determined by the dog 201. At the same time the pressure beneath the piston 212 is allowed to discharge through the pipe 285 past the lowered valve J and the pipe 286 into the discharge pipe 228. The lead 310 conducts power to the two solenoids 320 and 321, lifting both of the valves E and F. The lifting of the valve F permits pressure to pass from the pressure pipe 222 past the valve F into the pipe 290 to the feed cylinder 113 in a direction to feed the wheel toward the work, while the pipe 293 to the opposite end of the pressure cylinder is connected through the lifted valve E through the pipe 325 to the valve G. When the valve G is lowered when the switch 296 opens, the discharge passes freely through the pipe 292 to the discharge pipe 228. The closing of the switch 253 conducts power from the line 235 through the switch 253 to the lead 330 from which current passes through the lead 331 to the solenoid 332 of the valve D, causing this valve D to lift and allowing pressure from the pressure pipe 222 to pass through the pipe 333 past the valve D into the pipe 334 into the stop-selecting cylinder 294 beneath the stop holding piston 1340, lifting this so as to aline the finish stop 335 with the adjacent end of the feed piston rod 111. The lead 330 also passes to the finish selector switch 340 which can be placed on any of three points. As shown it is connected to the left hand point which connects through the lead 341 to the finish plug switch 89.

In the intermediate position of the selector asoaeea switch 340, connection is made from the lead 330 through the finish time delay at 345 and lead 346 to the finish feed switch 341. In the third position of the selector switch 340, connection is again made between the lead 330 and the lead 3 so as to connect with the plug gage switch 03. In either the first or third positions, therefore, it will be noted that the end of the finish grinding willbe determined by the entrance of the finish plug portion 4| into the work which closes the switch 89, and in the intermediate position of the selector switch 340, the end of the finish grind willl'be determined by the closing of the switch 341 try the finish stop 335.

Before the feed has brought the wheel into contact with the work, however, the motion of the rack bar III of the feed mechanism has rotated the quick approach cam ill into position to close the switch at 350, which establishes a connection from the line 235 through the switch 350 to the lead 35L energizing the solenoid 352 and raising the valve G. Raising of the valve G cuts of! the discharge from the pipe 325 to the pipe 292 which took place during the initial feed motion in an unrestricted manner, and causes this discharge from the pipe 325 to take place through the pipe 323 leading to the valve H. This valve is now in its raised position, its solenoid being energized from the lead 330, so that the discharge is forced to pass through the pipe 355, the finish grinding throttle valve 356, and the pipe 351 back to the discharge pipe 228. The rate of feed is then slowed to the relatively slow finish feed grinding rate, and it is moving at this speed when the wheel contacts with the work and until the finish grinding operation has been completed.

The completion of this operation is determined either by the entrance of the finish plug of the plug gage into the work, or by the closing of the switch 341, depending upon the setting of the selector switch 340. When this limit is determined by the finish stop 335, a further action of the grinding wheel may be permitted for a spark-out period, the extent of which is determined by the setting of the time delay 345. Whatever the setting of the selector switch is, however, either after this time delay, or immediately upon the closing of the plug switch at 33,

circuit is closed to the lead 360 which leads back to the lead 246 and to the cycle-actuating solenoid 239, which thus acts to step the cycle mechanism around to Load position.

In load position the switch-closing projections 11 on the disk 236a closes the switch 250, while all the other switches 25!, 252, 253 and 254 are open. The opening of the switch 254 which allows the valve K to fall, opens the pipe 2 leading to the control valve member 204 to discharge so that the member 204 drops to its lowest position so that on its outward stroke the wheel slide passes the dog 202 and comes to rest against a suitable stop without reversal of the direction of traverse.

The feed mechanism is also retracted, the valves E and F also being in lowered position and the finish stop moved out of operative position by the discharge of fluid from the pipe- 334 past the valve D.

The closing of the switch 250, energizing the lead 260, is also effective to lift the valve A which retracts the plug gage, and the energization of this lead 260 also energizes the cycle start switch 262 so that when this switch 262 is next closed, the cycle control mechanism will be stepped 12 around to its second position. In this stationary position of the machine, the finished work may be removed and a new piece or work introduced v The machine may then be started by the operator turning the member 204 to start the inward traverse of the grinding wheel, and as soon as this has been progressed to the point where the starting switch 262 is closed by the dog 300, the cycle control mechanism is actuated as previously described one step to Rough grinding. This allows the switch 250 to open, but the switches 25l and 254 are closed, both of the switch disks 2315b and 236e having the switchclosing projections b.

Closing of the switch 254, as previously described, causes the lifting of the valves E and F, starting the cross feed mechanism feeding the wheel toward the work. It also lifts the valve K which introduces pressure fiuid beneath the control member 204, lifting it to its highest position where the limits of traverse are determined by the dogs 200 and 20L All this is as took place in the finish grinding portion of the cycle.

The closing of the switch 25l, however, energizes a lead 365 connecting to the lead 366. This lead 366 connects to the rough grinding quick approach cam switch 361, so that when the fast feed has progressed to the desired predetermined point short of contact between the wheel and the work, this switch is closed, energizing the lead 368, leading to the lead 35!, raising the valve G, thus diverting the free discharge through the pipe 323 past the valve H. This valve H is now in lowered position, however, so that the discharge takes place through the pipe 310, through the rough grinding throttle valve 31! and the pipe 351, to discharge. This rough grinding throttle valve 31l may be set to a faster rate than the finish grinding throttle valve 356. The lead 346 also passes to the rough grinding selector switch 369, this being connected to the finish grinding selector switch 340 for simultaneous operation. In the left hand position of this switch 363, connection is made through the lead 310 to the rough grinding switch 00, and when this switch is closed, connection is made to the lead 360 so that the cycle solenoid 239 is actuated.

In the intermediate position of the rough grinding selector switch 360, connection is made through the lead 315 to the rough grinding time delay 316 from which connection is made through the lead 311 with the rough grinding limit switch 318. When this rough grinding switch 310 is closed by impingement of the rack bar III on the rough grinding stop 300, connection is made through the return lead 346 to time delay 316 and after the selected set time interval, the lead 360 sends an electric impulse to the cycle control solenoid 240 which will be energized to change the cycle setting. 7

It will be noted that in both the intermediate and right hand positions of the rough grinding selector switch 368, connection is made to the feed stops rather than to the plug gage. Thus in the first position of both of these switches, the limit of rough grinding and the limit of finish grinding will be determined by the plug gage. In the second position of these selector switches, the limits of rough and finish grinding will both be determined by the feed stop mechanism, while in the third position of the switches 369 and 340, the rough, grinding will be determined by the rough feed stop, and the finish grinding will be determined by the finish plug.

When the rough grinding has been terminated -ither by the rough grinding stop entering the work, or by contact of the rough finish stop. with any desired time delay for spark-out, the selector switch mechanism has been stepped aroundto the Dressing step of cycle, this completing the description of the various portion of the entire cycle.

At 400 there is shown a switch closed when the feed is fully retracted, this when closed energizing the lead 35l leading to the solenoid 352 of the quick approach valve G, causing this valve to be lifted in retracted feed position to cut out the fast feed by restricting the discharge to one or the other of the throttle valves 356 or 3'", depending on the position of the valve H. This is merely a safety feature by way of imposing a slight delay of the fast approach action at the start of the grinding phase.

From the foregoing description of an embodiment of this invention, it should be evident to those skilled in the art that various changes and modifications might be made without departing from its spirit or scope.

I claim:

1. In combination, a pair of supports, means for moving said supports relatively, electrical control means for said moving means, a rotary switch mechanism for actuating said control means in accordance with a predetermined cycle as said mechanism is being rotated, a ratchet and solenoid device for turning said mechanism step by step, means for momentarily energizing said solenoid when said supports assume predetermined relative positions to initiate such step by step motion of said mechanism, and means actuated by said mechanism during such turning to ene..gize said solenoid a second time to insure the completion of the actuating step of said mechanism.

2. In an internal grinding machine having a work support, a grinding wheel, a support for said grinding wheel, means for moving said supports relatively to cause the wheel to traverse work carried by said work support, and at times to extend the traverse to separate the wheel from the work, means to move said supports relatively to feed and retract the wheel relative to the work, means for truing said grinding wheel during the extended traverse, means for terminating the feed motion at either selected of two limits corresponding to rough grinding and finish grinding work sizes, respectively, sizing mechanism comprising a sizing plug gage having rough and finish size portions, and means for moving said gage to and from the work periodically, cycle control mechanism determining the sequence of operations of said moving means, and means for selectively operatively associating with said cycle control means said terminating means or said sizing mechanism when one of said gage portions enters the work.

3. In an internal grinding machine having a work support, a grinding wheel, a support for said grinding wheel, means for moving said supports relatively to cause the wheel to traverse work carried by said work support and at times to extend the traverse to separate the wheel from the work, means to move said supports relatively to feed and retract the wheel relative to the work, means for truing said grinding wheel during the extended traverse, a sizing mechanism comprising a plug a e having rough and finish size portions, means controlled by said support traverse moving means to actuate said plug moving means areas 1 in time therewith for moving said gage to and from the work periodically, a cycle control mechanism for controlling said moving means actuated in part by said sizing mechanism when one of said parts enters the work, and selectively actuated means for holding said plug gage retracted during the rough grinding portion of the cycle. 4

4. In combination, a pair of supports, one of said supports supporting work, a grinding wheel carried by the other of said supports, means for moving one of said supports relative to the other support to cause said grinding wheel to traverse work carried by said work support, a pair of stops carried by said one support projecting to different distances in the line of traverse and defining, respectively, grinding traverse limits and a limit for an extended traverse, a rockable and axially movable member positioned to be contacted by said stops at said respective limits to be rocked thereby and reversing the traverse direction, said member having three axial positions corresponding to grinding traverse, extended traverse, and a position out of contact with said extended traverse stop, hydraulic mechanism for placing said member in any selected of said positions, hydraulically actuated means for moving said supports relatively to feed and retract said wheel with respect to the work, wheel truing mechanism, hydraulically actuated means for moving said truing mechanism relative to said wheel into or out of truing relation thereto during such extended traverse, valves controlling said hydraulic mechanisms, 3, cycle control mechanism for actuating said valves in a predetermined sequence, and means controlled automatically as portions of said cycle are completed for actuating said cycle control mechanism.

5. In an internal grinding machine having a work'support, a grinding wheel, a support for said grinding wheel, means for moving said supports relatively to cause the wheel to traverse work carried by said work support and at times to extend the traverse to separate the wheel from the work, means to move said supports relatively to feed and retract the wheel relative to the work, means for truing said grinding wheel during the extended traverse, a sizing mechanism comprising a plug gage having rough and finish size portions, means actuated by said traversing support moving means for moving said gage to and from the work periodically in time with such traverse motion, a cycle control mechanism including a member movable to successive positions corre-' sponding to successive steps in the cycle of the machine and having means setting the various parts of the machine to perform such steps, and means actuated by the entry of one of said portions into the work to move said member to its next succeeding position.

6. In an internal grinding machine having a work support, a grinding wheel, a support for said grinding wheel, means for moving said supports relatively to cause the wheel to traverse work carried by said work support and at times to extend the traverse to separate the wheel from the work, means to move said supports relatively to feed and retract the wheel relative to the work, means for truing said grinding wheel during the extended traverse, a sizing mechanism comprising a plug gage having rough and finish size portions, means actuated by said traversing support moving means for moving said gage to and from the work periodically in time with such traverse motion, a cycle control mecha- 2,soa,eea

nism includinga member movable to successive positions corresponding to successive steps in the cycle of the machine and having means setting the various parts of the machine to perform such steps. means actuated by the entry of one of said portions into the work to move said member to its next succeeding position, and means actuable to hold said plug gage retracted during the rough grinding step in said cycle.

THOR H. IJUNGGREN.

REFERENCES CITED The following references are of record in the file of this patent:

Number 16 UNITED STATES PATENTS Name Date Guild May 12, 1931 Taylor May 12, 1831 Gallimore June 7, 1932 Stevens Aug. 1, 1933 Heald Feb. 27, 1934 Arms Feb. 9, 1943 Addicks et a1. Apr. 1, 1947 

